This invention generally relates to sensor systems, and more particularly to a computer module that communicates with a smart sensor system having activation alert capabilities.
Many electronic products, especially in the automotive and medical fields, require a rapid response to a sensed input signal. Input devices, such as smart sensors, are known which are used to evaluate the validity of an input signal prior to communicating an output signal for actuating an electronic system. Mechanical switches and relays which generate the input signals are electrically noisy when they change from open to closed or closed to open. The transition from a low input signal (i.e., an “off” position of the mechanical switch or relay) to a high input signal (i.e., an “on” position of the mechanical switch or relay) creates a signal bounce for a certain period of time. During this period of time, such as a time period of 60 milliseconds, the input device is uncertain whether the input signal is a true signal for which an output signal must be communicated to actuate the appropriate electronic system. Therefore, the input signal must be analyzed and filtered to determine whether a true signal change has occurred.
Smart sensors often include special circuitry or microprocessors to evaluate the validity of an input signal prior to communicating the output signal to the electronic system. The smart sensor utilizes the microprocessor or special circuitry to filter and evaluate the input signal while the input signal is bouncing. Once the smart sensor determines that the input signal is valid, the smart sensor communicates an output signal to a computer module of an electronic system.
Computer modules which control electronic systems often utilize sleep modes for preserving system power during periods of time in which the electronic systems are not in use. For example, a vehicle passive entry and starting (PASE) system may be programmed to enter a sleep mode when the vehicle is turned off. Therefore, the output signal communicated from the smart sensor will wake up the computer module of the electronic system. The computer module must then execute a startup and initialization sequence in which the circuitry of the computer module prepares to receive a valid output signal from the smart sensor and perform the functionality of the electronic system.
Disadvantageously, the amount of time required to startup and initialize the computer module is added to the amount of time required to debounce the input signal. That is, the reaction of the receiver module may be postponed until the start-up and initialization sequence is completed. Therefore, the electronic system reaction time is increased, which may result in an additional 50 milliseconds or more of reaction time. This additional reaction time may be unacceptable to a customer.
Accordingly, it is desirable to provide a computer module which can communicate with a sensor system having activation alert capabilities.